Who made you God?

How busy is Gilbert Castellanos, the tireless San Diego trumpeter who on Tuesday belatedly celebrates his eighth year as the host and star of his weekly jazz jam sessions at downtown's Onyx Room? Let us count the ways.

In addition to heading three bands of his own – the Gilbert Castellanos Quintet, the New Latin Jazz Quartet and the Latin Trumpet Summit – he is a member of guitarist Anthony Wilson's Nonet, saxophonist Charles McPherson's Quintet, drummer Willie Jones III's Quintet and the all-star Clayton Hamilton Jazz Orchestra.

There's more.

An adjunct instructor of jazz studies at USC's Thornton School of Music, Castellanos is also in demand for concerts and recording sessions. His many credits range from Diana Krall, Queen Latifah and Daniel Lanois to Horace Silver, Dr. John and, um, Belchfest. In virtually every instance, Castellanos is equally notable for his flawless technique, soulful delivery and his ability to play with skill and taste (two qualities not always found in the same artist).

Now 35, the Guadalajara-born, Fresno-raised trumpeter has been a San Diego mainstay since the mid-1990s, when his late-night jam sessions at El Campo Ruse helped propel the downtown jazz scene. He has been a standout not only as a versatile performer and bandleader, but as a driving force who has helped introduce literally thousands of young listeners to the joys of jazz.

The 10 p.m. jam sessions he leads nearly every Tuesday at the Onyx Room consistently draw enthusiastic crowds of fresh-faced fans. (Those fans, it's worth noting, rarely turn out for jazz shows at other area venues, but pack this Gaslamp Quarter club to enjoy the sizzling hard-bop, boisterous blues and svelte ballads that Castellanos and his quintet perform with a rotating cast of guest musicians.)

But even without any guest stars, you can count on Castellanos and his band to swing up a storm. Should you want to double your pleasure, he and his New Latin Jazz Quartet perform downtown Saturday at the all-ages Dizzy's.

Betcha his idea of relaxation is to join a drum circle

There's the drummer, but where's the band?

In the case of Zach Hill, who performs Sunday night at the Casbah, the drummer and the band are one and the same.

That's because Hill, best known for his work in math-rock favorites Hella and trip-hop mavericks Team Sleep, will be performing entirely on his own. More specifically, he'll be showcasing his free-jazz-inspired opus “Necromancer” in its 30-minute-plus entirety.

This should be quite a feat on stage, since the album version features Hill engaging in a spirited duet with Garage a Trois keyboardist Marco Benevento. The two performed “Necromancer” together 10 days ago at the Knitting Factory in New York (you can watch snippets on YouTube). But Benevento was apparently unavailable any other dates on this fearless drummer's ongoing U.S. solo tour.

Undaunted, he will vocalize as the spirit moves him and trigger samples with his hands and feet at the Casbah, where he will transform the high-octane “Necromancer” into a one-man musical dialogue with himself.